In ships of this type, methane is stored in liquid form and permanent evaporation inevitably takes place during transport.
Ships exist that are fitted with engines suitable for using the evaporated natural gas. Under such circumstances, the engines use two fuels, one of them a gas and the other a liquid, with the fuels being used in variable proportions.
In practice, the use of a gas fuel at a fraction lying in the range 30% to 70% leads to abnormal combustion which is difficult to control.
The invention seeks to remedy this drawback by providing an appropriate distribution of a set of cylinders as a function of the availability of gaseous fuel, thereby ensuring that when used, the gaseous fuel is used at a fraction which ensures good combustion.